DE 10 2005 040 952 A1 (corresponds to U.S. Pat. No. 7,232,323) describes such an electrical zero-force plug-type connector. The connector includes two housing parts in the form of a protective housing and a locking housing. The housings can insert into one another in first and second latching positions. The sleeve contacts hold open the tensioning sleeves, which are connected with the protective housing, when the housings are in the first latching position. As a result, the contact pins of a mating connector (i.e., an equipment connector) can be connected with little force to the sleeve contacts. Insertion of the mating connector releases the lock of the latching connection between the housings and brings the housings together into the second latching position. In the second latching position, the tensioning sleeves press the contact laminations of the sleeve contacts against the contact pins of the mating connector.
This latching mechanism enables the contact pins to be inserted freely. The contact force between the contact laminations of the sleeve contacts and the contact pins is produced in the final joining phase of the connector components. In order that mechanical stresses are not transmitted to the contact pins, a spring-loaded snap-fit rocker is integrally molded onto the outer wall of the protective housing. While joining to the mating connector, a spring arm of the rocker latches to a lug on the mating connector and form-fittingly connects both connector components to one another. The opening of this latching connection to separate the connector components can be achieved by exerting pressure on the free spring arm of the rocker.
Two acoustic or haptically detectable latching sounds occur sequentially over a short time interval during proper insertion while the connector components are joined to the mating connector. The two latching sounds respectively result from the latching of the protective and locking housings and the latching of the rocker of the protective housing on the mating connector.
As only one latching sound is produced with conventional connector components, a person making the connection might incorrectly conclude that the connector is assembled correctly upon hearing the single latching sound. If no mechanical stop exists in a form fitting manner between the connector components, then this can lead to faulty operation of the connection and to dangerous conditions in safety critical applications due to mechanical effects on the connection.